NECK INFLUENCE ON DYNAMICS OF CLUSTER RADIOACTIVITIES AND COLD FISSION

1990 ◽  
Vol 05 (26) ◽  
pp. 2101-2105 ◽  
Author(s):  
D. N. POENARU ◽  
M. MIREA ◽  
W. GREINER ◽  
I. CĂTA ◽  
D. MAZILU
Keyword(s):  
Lower Mass ◽  
Fission Process ◽  
Α Decay ◽  
Mass Asymmetry ◽  
Action Integral ◽  
Wide Range ◽  
Cold Fission

A two-center parametrization with smoothed neck is used to describe the shapes during the fission process of 234 U in a wide range of mass asymmetry (cold fission with 100 Zr fragment, 28 Mg radioactivity and α-decay). The optimum fission path has been found by minimizing the action integral. The neck influence is stronger for lower mass asymmetry.

Investigation of the synthesis of the unknown superheavy nuclei 309,312126

2019 ◽  
Vol 28 (07) ◽  
pp. 1950056 ◽  
Author(s):  
T. V. Nhan Hao ◽  
N. N. Duy ◽  
K. Y. Chae ◽  
N. Quang Hung ◽  
N. Nhu Le
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Charge Asymmetry ◽  
Evaporation Residue ◽  
Fission Process ◽  
Dinuclear System ◽  
Mass Asymmetry ◽  
Interacting Systems ◽  
First Time ◽  
Text Element

In this paper, we applied the method developed by Santhosh and Safoora in [Phys. Rev. C  94 (2016) 024623; 95 (2017) 064611] to theoretically investigate the fusion, evaporation-residue (ER) and fission cross-sections of the synthesis of the unknown superheavy [Formula: see text]126 nuclei produced by using the [Formula: see text]Ni + [Formula: see text]Cf and [Formula: see text]Zn + [Formula: see text]Cm combinations. The charge asymmetry, mass asymmetry and fissility of the DiNuclear System (DNS) in the synthesis of the mentioned combinations are also estimated. The calculated results show that the ER cross-sections for the synthesis of the [Formula: see text]126 nuclei are predicted to be much less than 1.0[Formula: see text]fb. In particular, it has been found that there may exist a valley of the ER cross-sections in the synthesis of a superheavy [Formula: see text] element, which produces the [Formula: see text]126 isotope. Subsequently, a model for the mass dependence of the ER cross-section in the synthesis of the [Formula: see text]126 isotopes has been proposed for the first time. On the other hand, the quasi-fission process strongly dominates over the fusion in the two concerned interacting systems. The present results, together with those reported in the previous studies, indicate that the investigated projectile–target combinations are not capable for the synthesis of the [Formula: see text]126 isotopes due to tiny fusion cross-sections (about 2–3[Formula: see text]zb), which go beyond the limitations of available facilities. Further studies are thus recommended to search for alternative interacting systems. In conclusion, this work provides useful information for the synthesis of the gap isotopes [Formula: see text]126, which have not been well studied up to date.

Inertia and fission paths in a wide range of mass asymmetry

1989 ◽  
Vol 333 (3) ◽  
pp. 291-298 ◽  
Author(s):  
D. N. Poenaru ◽  
J. A. Maruhn ◽  
W. Greiner ◽  
M. Ivaşcu ◽  
D. Mazilu ◽  
...  
Keyword(s):  
Mass Asymmetry ◽  
Wide Range

scholarly journals Molecular Vibrational States in the Binary Cold Fission of 252Cf

1997 ◽  
Vol 12 (18) ◽  
pp. 1343-1348 ◽  
Author(s):  
Ş. Mişicu ◽  
A. Săndulescu ◽  
W. Greiner
Keyword(s):  
Heavy Ions ◽  
Cluster Model ◽  
Vibrational State ◽  
Binary Fission ◽  
Vibrational States ◽  
Mass Asymmetry ◽  
Double Folding ◽  
Pole Configuration ◽  
Cold Fission

We predict a molecular vibrational state in the cold binary fission of 252 Cf using a simple decay cluster model. The Hamiltonian of two even–even fragments in the pole–pole configuration is built in the same fashion as that for the dinuclear molecule formed in heavy-ions collisions. The interaction between the two fragments is described by the double-folding M3Y potential. The spectrum of the butterfly vibrations is derived and its dependence on fragments deformation and mass-asymmetry is discussed. Some experimental implications are commented.

Surprisal approach in cold fission process

1981 ◽  
Vol 98 (4) ◽  
pp. 225-228 ◽  
Author(s):  
D. Otero ◽  
A.N. Proto ◽  
A. Plastino
Keyword(s):  
Fission Process ◽  
Cold Fission

scholarly journals Isotopic Compositions of Ruthenium Predicted from the NuGrid Project

2022 ◽  
Vol 924 (2) ◽  
pp. 88
Author(s):  
Seonho Kim ◽  
Kwang Hyun Sung ◽  
Kyujin Kwak
Keyword(s):  
Stellar Wind ◽  
Asymptotic Giant Branch ◽  
Lower Mass ◽  
Low Mass Stars ◽  
Isotopic Compositions ◽  
Carbon Abundance ◽  
Wide Range ◽  
Low Metallicity ◽  
Low Mass

Abstract The isotopic compositions of ruthenium (Ru) are measured from presolar silicon carbide (SiC) grains. In a popular scenario, the presolar SiC grains formed in the outskirt of an asymptotic giant branch (AGB) star, left the star as a stellar wind, and joined the presolar molecular cloud from which the solar system formed. The Ru isotopes formed inside the star, moved to the stellar surface during the AGB phase, and were locked into the SiC grains. Following this scenario, we analyze the Nucleosynthesis Grid (NuGrid) data, which provide the abundances of the Ru isotopes in the stellar wind for a set of stars in a wide range of initial masses and metallicities. We apply the C > O (carbon abundance larger than the oxygen abundance) condition, which is commonly adopted for the condition of the SiC formation in the stellar wind. The NuGrid data confirm that SiC grains do not form in the winds of massive stars. The isotopic compositions of Ru in the winds of low-mass stars can explain the measurements. We find that lower-mass stars (1.65 M ☉ and 2 M ☉) with low metallicity (Z = 0.0001) can explain most of the measured isotopic compositions of Ru. We confirm that the abundance of 99 Ru inside the presolar grain includes the contribution from the in situ decay of 99 Tc. We also verify our conclusion by comparing the isotopic compositions of Ru integrated over all the pulses with those calculated at individual pulses.

scholarly journals Lithium evolution from Pre-Main Sequence to the Spite plateau: an environmental solution to the cosmological lithium problem

2015 ◽  
Vol 11 (S317) ◽  
pp. 300-301
Author(s):  
Xiaoting Fu ◽  
Alessandro Bressan ◽  
Paolo Molaro ◽  
Paola Marigo
Keyword(s):  
Main Sequence ◽  
Big Bang ◽  
Stellar Atmosphere ◽  
Main Sequence Stars ◽  
Lower Mass ◽  
Big Bang Nucleosynthesis ◽  
Lithium Abundance ◽  
Wide Range ◽  
Nuclear Burning ◽  
And Diffusion

AbstractLithium abundance derived in metal-poor main sequence stars is about three times lower than the primordial value of the standard Big Bang nucleosynthesis prediction. This disagreement is referred to as the lithium problem. We reconsider the stellar Li evolution from the pre-main sequence to the end of main sequence phase by introducing the effects of overshooting and residual mass accretion. We show that 7Li could be significantly depleted by convective overshooting in the pre-main sequence phase and then partially restored in the stellar atmosphere by residual accretion which follows the Li depletion phase and could be regulated by EUV photo-evaporation. By considering the conventional nuclear burning and diffusion along the main sequence we can reproduce the Spite plateau for stars with initial mass m0=0.62–0.80 M⊙, and the Li declining branch for lower mass dwarfs, e.g, m0=0.57–0.60 M⊙, for a wide range of metallicities (Z=0.00001 to Z=0.0005), starting from an initial Li abundance A(Li) = 2.72.

Experiments on Lean Blowout and NOx Emissions of a Premixed Trapped Vortex Combustor With High G-Loading

2011 ◽  
Author(s):  
Jong Guen Lee ◽  
Jeffrey P. Armstrong ◽  
Domenic A. Santavicca
Keyword(s):  
Residence Time ◽  
Equivalence Ratio ◽  
Reaction Rates ◽  
Vortex Chamber ◽  
Nox Emissions ◽  
Lower Mass ◽  
Lean Blowout ◽  
Wide Range ◽  
Gas Flame ◽  
Trapped Vortex

The feasibility of a novel combustor concept (‘g-load’ combustion with trapped-vortex chamber) to extend the premixed lean-blowout (LBO) limit and to decrease NOx emissions was experimentally determined in a scaled-modular rig that simulated a commercial 250 kilowatt microturbine combustor. The effect of a wide range of g-load’s (770–5050) on the flame regime was identified. The natural gas flame was found to be stabilized in the trapped-vortex cavity (TVC) when the equivalence ratio was within a certain range near the lean blowout limits. The TVC extended the LBO limits to marginally lower mass-based equivalence ratio levels (5%). The LBO limits were found to decrease as the g-loads decrease and the residence time increases, indicating the increase of flame mixing and reaction rates with respect to g-load is not the reason for the extension of LBO limits. The increase of residence time of mixture in the TVC was the reason for the improvement of LBO limits. The new combustor concept would enable operation at lower equivalence ratios, reducing the NOx emissions as much as much as 30%. It also showed that when the flame is contained in the trapped vortex cavity, NOx is reduced compared to baseline combustion concept without TVC.

scholarly journals What do observations tell us about the highest-redshift supermassive black holes?

2019 ◽  
Vol 15 (S356) ◽  
pp. 261-275
Author(s):  
Benny Trakhtenbrot
Keyword(s):  
Black Holes ◽  
Large Scale ◽  
Big Bang ◽  
Supermassive Black Holes ◽  
High Mass ◽  
Host Galaxy ◽  
Host Galaxies ◽  
Lower Mass ◽  
Wide Range ◽  
Multi Wavelength

AbstractI review the current understanding of some key properties of the earliest growing supermassive black holes (SMBHs), as determined from the most up-to-date observations of z ≲ 5 quasars. This includes their accretion rates and growth history, their host galaxies, and the large-scale environments that enabled their emergence less than a billion years after the Big Bang. The available multi-wavelength data show that these SMBHs are consistent with Eddington-limited, radiatively efficient accretion that had to proceed almost continuously since very early epochs. ALMA observations of the hosts’ ISM reveal gas-rich, well developed galaxies, with a wide range of SFRs that may exceed ∼1000 Mȯyr−1. Moreover, ALMA uncovers a high fraction of companion, interacting galaxies, separated by < 100 kpc (projected). This supports the idea that the first generation of high-mass, luminous SMBHs grew in over-dense environments, and that major mergers may be important drivers for rapid SMBH and host galaxy growth. Current X-ray surveys cannot access the lower-mass, supposedly more abundant counterparts of these rare z ≳ 5 massive quasars, which should be able to elucidate the earliest stages of BH formation and growth. Such lower-mass nuclear BHs will be the prime targets of the deepest surveys planned for the next generation of facilities, such as the upcoming Athena mission and the future Lynx mission concept.

INFLUENCE OF ISOSPIN ON PRESCISSION PARTICLE EMISSION OF LIGHT FISSIONING SYSTEMS

2003 ◽  
Vol 12 (06) ◽  
pp. 817-826 ◽  
Author(s):  
W. YE
Keyword(s):  
Charged Particle ◽  
Statistical Model ◽  
Time Scale ◽  
Particle Emission ◽  
Fission Process ◽  
Mass Asymmetry ◽  
Hot Nuclei ◽  
Symmetric Fission ◽  
Very High ◽  
Α Particles

The isospin effect on particle emission for fissioning isobaric sources of 110Tc, 110Pd, 110In and for isotopic sources of 110,117,124In is explored in the framework of the Smoluchowski equation. A statistical model including dissipation is employed to study particle emission in asymmetric and symmetric fission of the In nucleus with different isospins. Calculations show that for a fissioning nucleus which has a larger isospin, charged particle multiplicities are no longer sensitive to dissipation strength or the fission time scale. Hence, for those systems with very high isospins, protons and α particles cannot be used as probes of the dissipation in the fission of hot nuclei. This conclusion does not depend on the mass asymmetry of the fission process.

Recent Applications of High Resolution Electron Microscopy to Crystalline Arrays of Virus Particles

1978 ◽  
Vol 36 (3) ◽  
pp. 470-482 ◽  
Author(s):  
R.W. Horne
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Analytical Techniques ◽  
Staining Technique ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Full Potential ◽  
Virus Particles ◽  
Resolution Electron ◽  
Wide Range

The technique of surrounding virus particles with a neutralised electron dense stain was described at the Fourth International Congress on Electron Microscopy, Berlin 1958 (see Home & Brenner, 1960, p. 625). For many years the negative staining technique in one form or another, has been applied to a wide range of biological materials. However, the full potential of the method has only recently been explored following the development and applications of optical diffraction and computer image analytical techniques to electron micrographs (cf. De Hosier & Klug, 1968; Markham 1968; Crowther et al., 1970; Home & Markham, 1973; Klug & Berger, 1974; Crowther & Klug, 1975). These image processing procedures have allowed a more precise and quantitative approach to be made concerning the interpretation, measurement and reconstruction of repeating features in certain biological systems.

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